In previous patent applications, the present inventor has reviewed the needs and uses for various safe (non-hazardous) preservative/fixative and embalming/preservative solutions for use in histology, cytology, embalming and anatomic examination procedures. These patents and patent applications include U.S. Pat. No. 5,290,760, U.S. Ser. No. 08/149,820, filed on Nov. 10, 1993, now U.S. Pat. No. 5,429,797, and U.S. Ser. No. 08/160,285, filed on Dec. 2, 1993, now abandoned, the entire specifications of which are incorporated herein by reference. These prior patents and patent applications all relate to solutions for preserving, fixing or embalming biological material.
Also in the group of relatively safe fixative compositions is U.S. Pat. No. 5,196,182 to Streck, which discloses certain antimicrobial compound-based fixative compositions, wherein the active, fixative compound is an antimicrobial compound that is reactive toward biological material. However, the compositions disclosed therein are in liquid form.
The various known aldehyde and antimicrobial agent-based fixative, preservative, and embalming solutions, as well as those disclosed in the patents and applications listed above, all contain one or more aldehyde or antimicrobial agents as the active (reactive) ingredient. The problem with all such solutions, however, is that these fixative, preservative, and embalming chemicals are relatively reactive materials that can easily lose their activity as well as form colored and insoluble polymerized materials when stored in aqueous solutions over time. These chemical reactions generally are oxidative, reductive and polymer-type reactions.
All of these reactive groups are polar in nature, and as such, they tend to be less reactive or non-reactive when stored in a solid anhydrous condition. However, there are two major problems connected with the preparation of anhydrous, solid forms of the types of aldehydes and antimicrobial chemicals that are useful in the compositions described herein.
First, the aldehydes and some of the antimicrobial chemicals described here occur only as liquids or aqueous solutions that cannot be dehydrated and formed into an anhydrous solid. Second, the reactive groups need to be stabilized in order to reduce their reactivity and to permit long-term storage, whether or not the chemicals occur in solid form.
In a few instances, all of the components in such preservative mixtures can be obtained individually in solid anhydrous forms, as is the case with some anti-microbial agent-based compositions. However, even in these few cases where dry powder blends of the mixtures is can be prepared, there is still a need for long-term stabilization of the mixture. The fact that the chemicals may be available in solid form does not does not appear to lessen the need for stabilization when the individual solid components are mixed together.